Treatise Online no. 45: Part N, Revised, Volume 1, Chapter 21: Cementing Bivalvia

Palaeoecology of Chondrodonta (Bivalvia) from the lower Aptian (Cretaceous) Apulia Carbonate Platform (Gargano Promontory, southern Italy)

“…The Mesozoic cementers predominantly inhabited shallow water environments, where some gregarious forms (e.g., lithiotids, rudists, oysters) originated highly dense aggregates (bivalve mounds, reefs, pavements, carpets), influencing the sedimentation rates and carbonate platform dynamics (e.g., Fürsich et al, 1994;Gili et al, 1995;Riding, 2002;Fraser et al, 2004;Skelton and Gili, 2012;Harper, 2012;Posenato and Masetti, 2012;Bassi et al, 2017). Despite the high abundance, widespread geographic diffusion and long-time ranging distribution, little is known about the functional morphology of the shell, taphonomy and geometries of the Chondrodonta accumulations.…”

“…Cementers predominantly inhabited shallow water environments, where some gregarious forms (e.g., lithiotids, rudists, oysters) formed highly dense aggregates (bivalve mounds, reefs and pavements), influencing the sedimentation rates and carbonate platform dynamics (e.g., Fürsich et al, 1994;Gili et al, 1995;Riding, 2002;Fraser et al, 2004;Skelton and Gili, 2012;Harper, 2012).…”

“…The cementing bivalves are characterized by high intraspecific morphological variability related to the substrate consistency and nature (e.g., rocky or shelly), wideness of the attachment area and, for gregarious species, spatial competition. Bivalves with small attachment areas and living in calm environments with high sedimentation rates show the tendency, during early ontogenetic stages, to raise the ventral margin from the substrate (e.g., Harper, 2012) and to develop an upright shell growth. Consequently, during the juvenile stage, the upright growth direction represents a secondary adaptation towards soft bottom environments.…”